Discoveries and inventions of the nineteenth century (1905)
Routledge, Robert · London : G. Routledge and Sons · leaf 513
e diameter of the blind spot is consider-able compared with the size of the retina,its greatest diameter being about -^g^j in.The length on the retina of the image of a man at a distance of 6 ft. or 7 ft.is not greater than this, so that in a certain position with regard to the eyea person would,… … 462 SIGHT. Taecomes invisible, and would be so even if its apparent diameter wereeleven times greater; so that if we suppose eleven full moons ranged in aline, the whole would be quite invisible to a person looking towards a cer-tain point of the sky at no great angular distance from them. The…
Inventions
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